Threaded snap in connector

ABSTRACT

The disclosure shows an electrical connector with both a snap ring and threaded end for fastening the connector to an access hole in an electrical junction box. The snap ring has snap lock tangs to hold the connector in the box and resist pull out forces. The snap ring also has grounding tangs for grounding the connector. Also, the connector has locking tabs that are designed to be seated in apertures located in the leading end of the connector. The connector has a threaded leading end having a standard pitch, which has been truncated to a smaller diameter. As the snap ring is very thin, it can be easily stamped from thin spring steel or its equivalent and mass-produced at a low unit cost. The snap locking tangs are deflected inward as they are pushed into a typical access hole in an outlet box or electrical panel. The thinness of the snap ring wall and its slightly bowed shape permits the snap ring to enter the hole of the electrical junction box and lock the ring and connector together to resist being pulled out. If the installer feels the connector should be threaded into a threaded access aperture or that a standard lock nut should be installed; it is only necessary to use a screwdriver, other tool or manually remove the snap ring and expose the truncated threads.

FIELD OF THE INVENTION

The present invention relates to devices for connecting cables andelectrical tubing to electrical panels or junction boxes andspecifically to a device that is easier to use in a more universalmanner than current connectors that are commonly used in the trade.

BACKGROUND OF THE INVENTION

It is common in the electrical industry to connect cable and electricaltubing to electrical junction boxes by means of a variety of standardthreaded connectors. The exterior threaded portion of the connectors arepushed into a standard access hole in a junction box or electrical paneland held in the hole by a standard lock nut. This standard lock nut hasan interior-thread, which is screwed onto the exterior-threadedelectrical connector that extends into the junction box. The lock nuttypically has one or more individual threads on its interiorcircumference to create a locking grip against the wall of the junctionbox. Sometimes the access hole has internal threads into which theconnector is threaded. In that case, no lock nut is needed. Lock nutsused in the electrical trade are commonly formed of metal that is 0.130inches or more in thickness.

Also, snap fitting connectors are becoming more popular in situationsthat do not require a threaded lock nut.

While snap fitting connectors have become important, they are stilllimited to those installations where a locking nut is not desired or athreaded receiver access hole are not present.

Therefore, an acceptable and versatile snap fitting connector or snapring that can also be removed for use with threaded lock nuts orthreaded receptacles is very much needed. Efforts have been made in thepast to achieve these goals, but the prior efforts are not believed tohave been successful.

SUMMARY OF THE INVENTION

This invention provides a snap ring and threaded electrical connectorthat is much easier to use in a universal and versatile manner than thecurrent connectors used in the trade. The snap ring is stamped from asingle thin piece of spring steel or its equivalent. In the stampingprocedure, locking tabs are formed to define portions that are bentinward to form locks for mating with apertures located in the leadingend of a special connector and portions that form snap locking tangs.The stamped piece of spring steel is formed into a circular or annularshape thereby creating a ring shaped snap ring with snap locking tangsslanted to the rear and outward to snap in an access hole in anelectrical junction box to prevent pull out. The snap ring also hasinward and forward slanting locking tabs around its outer periphery tolock the locking tabs to an aperture in the forward portion of theelectrical fitting. The locking tabs within the snap ring are sized,positioned and shaped to fit into the mating aperture in a manner itcannot be pulled forward or rotated relative to the connector. As usedherein, the aperture is defined to include an opening or a lockingrecess as the aperture can be either open at the bottom or have a thinbottom wall. The thickness of the snap ring and its shape is critical asit must fit into the space between the outside diameter of the threadedportion of the connector with standard threads and the inside diameterof the standard access holes in the electrical junction box or panel.Grounding tangs are also lanced rearwardly and outwardly to provide agrounding contact.

To apply the snap ring with the threaded connector, the snap ring isplaced over the threaded leading end with the locking tabs located inthe locking apertures. The assembled connector and snap ring is thenready for use. When used, the installer simply has to insert theassembled connector into the access hole in the junction box until theflange prevents further insertion. During insertion, the snap lockingtangs are forced inwardly by the sidewalls of the junction box holeuntil the tangs are completely through the hole at which time they snapback and prevent withdrawal. This is a single hand job and makesinstallation efficient and easy, even in difficult positions. Theinvention permits the use of the special connector of the invention withstandard cable and electrical tubing with standard electrical junctionboxes having standard holes.

In the event, it is desired to remove the snap ring, such can readily bedone by a screwdriver or other tool or manually to unlock and remove thering from the remainder of the fitting. This exposes the screw threadfor use with a standard lock nut either when there is no thread openingin an electrical box or permits the connector to be threaded into athreaded receptacle.

Other advantages of the present invention will be better understood fromthe following description when read in conjunction with the appropriatedrawings.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view of the annular snap ring in place on a connector andmounted in the outer wall of an electrical junction box.

FIG. 2 is a view of the connector of FIG. 1 with the annular snap ringand junction box wall omitted.

FIG. 3 is a plan view of the blank used to form the snap ring of thepresent invention.

FIG. 4 is an end view of the annular shaped snap ring formed from theblank shown in FIG. 1.

FIG. 5 is a side view of FIG. 4 with the leading end on the right.

FIG. 6 is a side view similar to FIG. 5 with the trailing end on theright.

FIG. 7 is a view similar to FIG. 4 except viewed from the opposite side.

FIG. 8 is a cross sectional view of the connector of FIG. 2.

FIG. 9 is a cross sectional view similar to FIG. 8 but rotated ninetydegrees.

FIG. 10 is a view similar to FIG. 9 but showing a lock nut prior tobeing assembled to lock the connector into position.

FIGS. 11 to 13 show an alternative preferred embodiment similar to FIGS.3 to 5.

DESCRIPTION OF THE INVENTION

The present invention comprises an annular snap ring and threadedelectrical connectors for use with standard electrical junction boxes,including electrical panels and the like.

With reference to FIG. 3, there is shown a plan view of the blank 11used to form the snap ring.

The blank is typically stamped from a thin piece of spring steel, suchas 1050 spring steel or equivalent, preferably 0.017 to 0.018 inches inthickness but may be 0.013 to 0.022 inches in thickness. The blank 11has a tongue 12 on one end and a groove 14 on the opposite end. U-shapedopenings 30 in the blank 11 define tabs or tangs, which are lanced fromthe body of the blank. The U-shaped openings have relatively wide slots32 on each side of the tabs or tangs and a narrow slot or shear line 31at the bottom of the U-shape. The snap locking tangs 16 are bentoutwardly and rearwardly. Locking tab 18 is bent inward and forwardly.Two slits or narrow openings 34 in blank 11 define grounding tangs 36that are bent outward and rearwardly adjacent the trailing edge 35. Theflat front surface of blank 11 shown in FIG. 3 will become the outercircumference 26 when it is formed into the annular shape of the snapring.

As shown in FIG. 1, edge 22 is the forward or leading end of the snapring facing into the interior of a junction box and edge 24 is therearward or trailing edge facing away from the junction box.

FIG. 4 depicts an end view of blank 11 after it has been formed in acircle or annular shape. Snap locking tangs 16 are angled outwardly andrearwardly from the face 25 of blank 11. The locking tab 18 is angledinwardly and forwardly from face 25. Grounding tang 36 is angledoutwardly and rearwardly.

When blank 11 is formed into an annular shape, tongue 12 loosely fitsinto groove 14. The blank formed into an annular snap ring 50 isdepicted in FIG. 4. Usually, the spring steel is heat treated after theforming operation so that the steel will have the correct properties andso that it will hold the annular shape. The blank 11 is approximately0.375 inches wide and 2.750 inches long prior to being formed in theannular shape.

Snap locking tangs 16 with outer or abutment edges 38 extend and areangled outwardly and rearwardly from the outer circumference 26 of thesnap ring 50 and are located preferably at approximately 180 degreesfrom each other.

The snap locking tangs form an outermost diameter of 1.00 inches for a ½trade size connector. Except when specifically indicated otherwiseherein, all dimensions are with reference to a ½-inch trade sizefitting.

The locking tabs 18 are located approximately 180 degrees apart andextend inwardly and forwardly from the inner circumference 28 at theapproximate angle shown. The locking tabs 18 project typically 0.06inches inwardly and are each approximately 0.125 inches in width.

The locking tabs 18 drop into the apertures 20 so that the abutment edgecontacts the vertical or forward wall 21 so that the snap ring isprevented from linear movement with respect to the connector in theforward or leading direction. The snap ring is prevented from linearmovement in the opposite direction by the forward wall 43 of flange 45.The locking tabs 18 are also prevented from rotating relative to theconnector by the side walls 17 of the locking tabs 18 being in contactwith the vertical side walls 19 of the apertures 20. Thus, the snap ringis locked onto the connector unless a tool or fingers are used to raisethe locking tab 18 out of the aperture.

FIG. 1 depicts the annular snap ring 50 and connector 40 fastened to anelectrical junction box wall 46. To apply the snap ring 50, it is firstfastened on the external threaded end 42 of the connector 40. Thisusually slightly stretches the diameter of the ring.

The connector 40 has a trailing end 37, which represents the entirerange of various electrical connectors that may be used for clamping acable or conduit. For illustrative purposes, there is shown a body 44with a threaded screw hole 68 for receiving a clamping screw.

The abutment edge 64 of locking tabs 18 engage the forward wall 21 (SeeFIG. 9) of apertures 20 located in the leading end of the connector. Thesides 19 (See FIG. 10) of the aperture 20 keep the locking tabs 18 fromrotating relative to the connector 40. The aperture is approximately0.020 inches wide and 0.020 long and may be bottomless or may have athin bottom.

As the connector 40 and snap ring 50 is pushed into the access hole orknock-out 48, the locking tangs 16 are forced inward toward the centralaxis of the annular snap ring. The spring steel material of constructionof the snap ring 50 allows the locking tangs to flex inwardly toward thecentral axis. When the snap ring 50 is advanced sufficiently into theaccess hole 48, the locking tangs spring outward as their abutment edges38 pass completely through the electrical junction box wall 46. As aresult, the connector 40 is locked tightly into place on each side ofthe wall 46 between the forward wall 43 of flange 45 of the connector 40on one side abutted with the outer surface 60 of the junction box wall46 and the locking tangs 16 abutted with their abutment edges 38 againstthe inner surface 58 of the junction box wall 46.

When installed in a junction box, as depicted in FIG. 1, the leadingedge 22 of the snap ring is inside the junction box and the outer ortrailing edge 24 is within the confines of the access hole 48 and facingflange 44 of the connector. The grounding tangs 36 extend outwardapproximately 0.020 inches and are forced inward by the inside wall ofaccess hole 48 so that the trailing grounding edge 35 of the groundingtang makes firm contact with the side walls of the access hole 48 of theelectrical junction box. The connector is highly resistive to pull outforces when the connector 40 and snap ring 50 are locked in place.

The outer diameter of the annular snap lock ring in its relaxed orunstretched shape is preferably circular and, as measured from its outersurface 52, is approximately 0.875 inches in diameter for ½-inch nominaltrade size threads. The dimensions of the snap lock ring mentionedherein are for use with a threaded connector having ½ inch NPS (NationalPipe Straight) or NPT (National Pipe Taper) trade size threads.

As seen in FIG. 5, the ring is slightly bowed outward with a dividingline 54 for the outward bow approximately 0.145 inches from the rightend. The outside diameter of the leading end 56 has an outward diameterof approximately 0.836 inches and the outside diameter of the trailingend 62 is approximately 0.836 inches.

With reference to FIG. 10, there is shown the connector of thisinvention with nominal size threads 66, which have been slightlytruncated at 67. The threads are of standard pitch and depth but theslight truncation at 67 which is flat or slightly rounded to reduce thenormal maximum diameter of the threaded portion. This is typicallyapproximately {fraction (1/32)}″ in width. As used herein a truncatedthread is meant to be a nominal trade size thread which has the crest ofthe thread slightly flattened or rounded to reduce the major diameter.Otherwise, the thread is unchanged and when the snap ring is removed,can be readily threaded into the threaded opening of a junction box orcan be used with a standard lock nut 70.

The nominal knockout or access hole for an electrical junction box is0.875 inches in diameter. Usually the manufacturer provides an opening0.870 to 0.880 inches in diameter. However, the access hole can be assmall as 0.859 inches in diameter (including tolerances).

The snap ring could be constructed for other standard trade size threadsby scaling these dimensions appropriate to the nominal trade sizes suchas for nominal trade sizes ¾ inch or 1 inch.

With reference to FIGS. 11, 12 and 13, there is showed views similar toFIGS. 3, 4 and 5 and similar numbers are used. The alternative andpreferred embodiment is shown in these figures where the snap lockingtang 16 and locking tab 18 share a common shear line 72 which defines anarrow separation line. There is also provided a small half-circularcutout 74 at each end of the shear line located adjacent narrow slot 31and 33, respectively. A singular relatively wide slot 32 is providedadjacent each snap locking tang 16 and locking tab 18 on the oppositeside from common shear line 72. Shown on FIG. 12 is the central axis 76of the snap ring.

The nominal major diameter of the threads 66 is normally approximately0.803 to 0.806 inches but in actuality approximately 0.798 to 0.799inches after this has been reduced by the truncated crest 67. Thisleaves sufficient space between the major truncated diameter and theminimum diameter of 0.859 inches for the access hole to accommodate thethickness of the wall of the snap ring.

Thus, the invention defines a versatile threaded snap in connector thatis readily utilized by electricians to connect cable and electricaltubing to electrical junction boxes by the easily applied snap infeature; but, at the same time can be utilized to make the connection bylock nut or by threaded access holes. To expose the threads for thethreaded connection, it is only necessary to remove the snap ring.Because of this arrangement, the electrician can minimize the inventoryand only take one threaded snap in connector for a job.

Having thus described the invention with reference to preferredembodiment, it is to be understood that the invention is not so limitedby the description herein but is defined as follows by the appendedclaims.

What is claimed is:
 1. A threaded snap in connector for attachment to anelectrical junction box: A connector having a trailing end portion; Aleading end portion on said connector; A flange separating said trailingend portion from said leading end portion; Truncated normal size threadson said leading end portion; A locking depression located in saidleading end portion; A removable annular shaped metal snap ring having athickness approximately 0.013 to approximately 0.022 inches surroundingsaid leading end portion; A locking tab on said snap ring extendinginwardly from said snap ring into said depression to prevent said snapring from being removed in a linear forward direction from said threadedportion; A snap locking tang on said snap ring and extending outwardlyto resist the connector from being pulled from an electric junction box;and A longitudinal split in said snap ring.
 2. The connector of claim 1where said annular shape snap ring has a first end in the form of atongue and a second end in the form of a groove with said two endsmeeting each other to complete the annulus.
 3. The connector of claim 1where said annular shaped snap ring has a thickness of fromapproximately 0.017 to approximately 0.018 inches.
 4. The connector ofclaim 1 where said annular shaped snap ring has a trailing edge and agrounding tang extending outward and rearwardly from said annular shapedsnap ring.
 5. The connector of claim 1 where said locking tab is angledinwardly and forwardly.
 6. The connector of claim 5, wherein saiddepression further includes: A vertical forward wall in said aperture;An abutment edge at the end of said locking tab; and Said abutment edgeabutting said vertical forward wall to prevent said annular shaped snapring from moving forward in a linear direction.
 7. The connector ofclaim 6, which further includes: Said depression in the form of anaperture; Two opposite side walls in said aperture; Two opposite sidewalls on said locking tab; and Said side walls on said locking tabadjacent said side walls in said aperture to prevent said annular shapedsnap ring from rotating relative to said connector.
 8. The connector ofclaim 1, which further includes: Said locking tab is angled inwardly andforwardly with two sides; Said snap locking tang is angled outwardly andrearwardly with two sides; and A common side shared between said lockingtab and said snap locking tang.
 9. The connector of claim 1 wherein saidannular shaped snap ring has a central portion which is bulged outwardto a larger diameter and a leading outside diameter and a trailingoutside diameter that is smaller than said bulged outward largerdiameter.
 10. An electrical junction box connector comprising: Anelectrical junction box having an access hole, with an inside wall insaid access hole of a standard trade size; A threaded snap in connectorattached to said electrical junction box through said access hole; Atrailing end portion on said connector; A leading end portion on saidconnector; A flange separating said trailing end portion from saidleading end portion; Truncated threads on said leading end portion; Alocking depression located in said leading end portion; A removableannular shaped metal snap ring having a thickness approximately 0.013 toapproximately 0.022 inches surrounding said leading end portion; Alocking tab on said snap ring extending inwardly from said snap ringinto said depression to prevent said snap ring from being removed in alinear forward direction from said leading end portion; A snap lockingtang on said snap ring and extending outwardly to resist the connectorfrom being pulled from said electric junction box; and A longitudinalsplit in said snap ring.
 11. The junction box connection of claim 10wherein said snap ring wherein said split is defined by a first end inthe form of a tongue and a second end in the form of a groove with saidtwo ends meeting each other to complete the annulus at said split. 12.The junction box connection of claim 10 where said annular shaped snapring has a thickness of from approximately 0.017 to approximately 0.018inches.
 13. The junction box connection of claim 10 where said annularshaped snap ring has a trailing edge and a ground tang in electricalcontact with said inside wall of said access hole.
 14. The junction boxconnection of claim 10 where said locking tab is angled inwardly andforwardly.
 15. The junction box connection of claim 14 wherein saiddepression is in the form of an aperture and further includes: Avertical forward wall in said aperture; Two opposite sidewalls in saidaperture; An abutment edge of the end of said locking tab; Two oppositesidewalls on said locking tab; Said abutment edge abutting said verticalforward wall to prevent said annular shaped snap ring from movingforward in a linear direction; and Said side walls on said locking tabadjacent said side walls in said aperture to prevent said annular shapedsnap ring from rotating relative to said connector.
 16. The junction boxconnection of claim 10 where said annular shaped snap ring is bulgedoutward to a larger diameter and a leading outside diameter and atrailing outside diameter that is smaller than said bulged outwardlarger diameter.
 17. A method of making an electrical junction boxconnection including the following: Providing an electrical junction boxhaving a wall and an access hole, with an inside wall in the accesshole, of a standard trade size; Providing a threaded snap in connectorhaving a leading end portion with truncated threads and a trailing endportion and a flange, separating the trailing end portion and saidleading end portion, with threads on the leading end portion; Providinga locking depression; Providing a removable annular shaped split metalsnap ring surrounding the leading end portion having a metal thicknessapproximately 0.013 to approximately 0.018 inches; Providing a lockingtab on said snap ring angled inwardly and forwardly and entering thedepression to prevent the snap ring from moving forwardly with respectto the connector and to prevent rotation with respect to the connector;Providing a snap locking tang on the snap ring angled rearwardly andoutwardly; Determining whether to use a threaded connector of a snapring for holding the connector to the junction box; If the decision isto use a snap ring: Pushing the connector toward the access hole withthe snap locking tang being forced inward until the junction box wall iscleared and snap locking the connector to the junction box; If thedecision is to use a threaded connector: (1) Removing the annular ringby lifting the locking tab out of the depression; (2) Providing eitheran access hole with a threaded opening or a threaded lock nut; and (3)Screwing the connector into the threaded access hole or pushing theconnector into the access hole and holding in place by a locking nut.